The present invention relates, in general, to the field of serial communication interfaces and methods for a local area network controller.
More particularly, the present invention relates to a serial communications interface which connects the physical layer to the media access control layer of a local area network. The serial communications interface of the present invention is utilized to transfer serial data to and from a local area network controller such as a large scale integration (LSI) communications protocol integrated circuit.
A local area network node or station can be broken down into several layers. The first of these is the physical layer, or modem, which takes analog signals from the network cable and decodes them into digital signals. These digital signals are then passed to the media access control (MAC) layer which thereupon decides what to do with the data. The MAC also creates messages which it passes to the physical layer to be converted into the appropriate analog signals. The controlling of these layers is done by an entity called station management (SM) which must be able to talk to each of these layers in turn.
Therefore, the interface between the physical layer and the rest of the station has a several requirements. First, serial digital data must be passed between the physical layer and the MAC layer in both directions. Secondly, station management must have some means of communicating to and from the physical layer. Station management must be able to turn the physical layer transmitter off, and station management must know whether the physical layer is not receiving data as well as other similar functions. Finally, station management must have some means of communicating to and from the physical layer. At present, existing local area network (LAN) controllers utilize a simple interface which pass serial communications only.